Clutch slips when engine hot

[motorbiketim]

My clutch works great until after I ride the bike for about twenty minutes, then it slips so bad I can hardley get the bike moving. I replaced the clutch and springs about two years ago. Could it be too much fluid in the reservoir or the oil level too high??? I think that I used wal-mart 10W40 when I changed the oil over the winter and I have never had problems with this oil before.

 

Any help much appreciated!

Tim

[rhncue]

My clutch works great until after I ride the bike for about twenty minutes, then it slips so bad I can hardley get the bike moving. I replaced the clutch and springs about two years ago. Could it be too much fluid in the reservoir or the oil level too high??? I think that I used wal-mart 10W40 when I changed the oil over the winter and I have never had problems with this oil before.

 

Any help much appreciated!

Tim

 

It could be a couple of things but to much fluid in the master can cause that. There also is a tiny hole in the bottom of the master where the piston slides through. This hole relieves the fluid pressure when the brake lever is relaxed. If this hole is clogged this can occur as the clutch is never fully released.

 

Dick

[RedRocket]

It's not that hard to take some fluid out of your reservoir, so why don't you start there, and report back?

[utadventure]

Make sure the fluid in the line between the Master and the Slave cylinders is fresh. Brake fluid is hygroscopic (absorbs water) and can effect the clutch like you're talking. The water gets hot, expands and then partially disengages the clutch plates from the motor.

 

Good luck!!

[Yammer Dan]

As said think you need a good flushing and cleaning with new fluid. Flush out old and clean out master good.

[sarges46]

Ok...good ideas....now by any chance did you put energy conserving oil in? If you did that might just be it. Check the round stamp on the back....if it says energy conserving on it you might want to change your oil to something that doesnt say that.

[motorbiketim]

Thanks for the input. I drained about 1/4 cup of engine oil out - it was a bit overfilled. Also, bled a little brake fluid off at the slave cylinder and found that I had the clutch line laying against the coolant hose so perhaps the heat from the hose was causing the fluid to expand??? Anyway I took the bike out for a ten minute ride and it seems fine so far, we'll see how the ride home from work goes later.

 

Tim

[MiCarl]

... found that I had the clutch line laying against the coolant hose so perhaps the heat from the hose was causing the fluid to expand???

 

Heat will cause the fluid to expand. Most of the expansion is in the clutch slave cylinder which is bolted up to the side of the engine and gets good and hot. That's what the little tiny hole in the bottom of the master cylinder is for - to let fluid back out of the slave and lines and into the reservoir.

 

That little hole needs to be unobstructed and there needs to be room in the master cylinder for the fluid.

 

Clutches are a bit different than brakes. As the clutch wears the fluid in the reservoir will rise, which is the opposite of brakes. On the clutch you want to be above the minimum level but not clear to the top.

[motorbiketim]

Heat will cause the fluid to expand. Most of the expansion is in the clutch slave cylinder which is bolted up to the side of the engine and gets good and hot. That's what the little tiny hole in the bottom of the master cylinder is for - to let fluid back out of the slave and lines and into the reservoir.

 

That little hole needs to be unobstructed and there needs to be room in the master cylinder for the fluid.

 

Clutches are a bit different than brakes. As the clutch wears the fluid in the reservoir will rise, which is the opposite of brakes. On the clutch you want to be above the minimum level but not clear to the top.

 

My fluid level is fine and the fluid is clean but where is this tiny hole???

[raceman62race]

If I had this problem I would ride the bike until it got hot and started slipping. Then I would switch the engine off and open the bleeder valve on the slave cylinder as quickly as I could. If much more than a small dribble of fluid came out, your not releasing pressure from the slave cylinder. If not much fluid comes out, you can assume everything is working correctly except for the clutches themselves. This should be a way to sort of cut the system in half and point you in the right direction

[Squidley]

Good advice by all here, but if you haven't changed out the brake fluid in all the master cylinders of the bike, I would suggest you do it. Check and make sure that the oil hasn't been changed to an energy conserving one, stranger things have happened.

[Condor]

My fluid level is fine and the fluid is clean but where is this tiny hole???

 

With the cover off the reserve you'll see a hole in the bottom plus another to the left that looks like someone started to drill a hole and changed their mind. There's a very tiny hole at the bottom. To see if it's plugged 'gently' squeeze the clutch lever just a tad. If the hole is open the surface of the fluid will deform... sorta make a small mound. Squeeze the lever hard and you'll be cleaning up DOT 3 off your fairing. If you don't see any evidence of fluid coming out of the hole then you need to clean it. The wire out of one of those wire ties that you get in the produce section of your local market will be about the right size to clean it out. Once the hole has been cleared, bleed the 'H' out of system. Old fluid will sometimes create crystals in the lines. All it takes is one minute piece of dirt or crystal to mess up your hole day....

[motorbiketim]

Thanks again,

It was working fine until I flushed the system out with new fluid over the winter so I must have dislodged some gunk. I cleaned it out with a tiny piece of wire today so hopefully this will fix it.

 

Tim:97:

[Condor]

Thanks again,

It was working fine until I flushed the system out with new fluid over the winter so I must have dislodged some gunk. I cleaned it out with a tiny piece of wire today so hopefully this will fix it.

 

Tim:97:

 

Don't forget to flush.....